LINTHICUM - The Federal Aviation Administration has begun planning for a new air traffic control tower at BWI Thurgood Marshall Airport.The FAA is in the early stages of planning for the tower, and the agency is currently determining when funding may be available, said Arlene Salac, a spokeswoman for the agency."The airport will work with the FAA regarding a site for the tower, should the project move forward," BWI spokesman Jonathan Dean said.The FAA, officials said, considers many factors before deciding whether to renovate existing air traffic control towers or build a new facilities. These include age, size, height, location and condition.The BWI air traffic control tower is approximately 100 feet high, according to the airport website. It operates 24 hours a day, seven days a week, all year, according to a pilot's guide to the facility.The Maryland Aviation Administration capital budget lists the cost of replacing the tower as $21 million, although other reports on the plan have put the price at more than $26 million.The FAA "also looks at forecast air traffic operations, future staffing and planned new technology and equipment before deciding whether to renovate the facility or build a new tower," Salac said.